Feed units can serve to effect a rigid, variable-length connection between two points of articulation. They can be used in different technical fields, for instance, on machine tools also designated as “parallel kinematics machines” (PKM). The integrated drive and a measuring system enable a controlled variation of the length of a feed unit. The function of the feed unit is comparable to that of an extendible strut. A parallel kinematics machine can be equipped with three or six such units.
A feed unit known from the published document DE 36 42 938 C2 serves as a power actuating device with a lifting mechanism for a tipping apparatus of a driver's cabin of a truck. A rotary drive transmission mechanism with a motor that is disposed outside the housing of the actuating element is associated to the lifting mechanism. This device therefore has a complicated structure and is not lash-free and has a low axial rigidity and a large design space requirement, so that it is not suitable for use on a machine tool.
The published document JP 11-299 169 A shows a feed unit of the initially cited type. Concrete specifications as to the possibility of an articulated retention of this unit on a connecting structure are not disclosed in this document.